Such a bearing device has a rolling bearing with a double raceway and a hub wheel. A drive shaft as a rotation shaft for a driving wheel includes a small diameter shaft portion and a large diameter shaft portion. The small diameter shaft portion of the drive shaft is fitted into a central hole of the hub wheel for rotation as a unit therewith while the large diameter shaft portion protrudes from the central hole of the hub wheel to a vehicle inner side. The rolling bearing has an inner ring which is fitted on an outer peripheral surface of the vehicle inner side of the hub wheel. The large diameter shaft portion and the inner ring are adjacent to each other in an axial direction, and their heights in a radial direction are approximately the same.
Such a bearing device is provided with, as a rotation detection device, a pulser ring which rotates with the inner ring as a unit to generate rotation magnetic information and a magnetic sensor having a detection element for detecting the magnetic information from the pulser ring.
The pulser ring is arranged on the outer peripheral surface of the vehicle inner side in a narrow annular space between the inner ring and the outer ring of the rolling bearing, which results in a low radial arrangement height from the outer diameter surface of the inner ring.
Therefore, when the magnetic sensor is positioned on an outer diameter surface of the large diameter shaft portion of the drive shaft to face the pulser ring in the axial direction, the radial arrangement height thereof becomes low corresponding to the low radial arrangement height of the pulser ring.
For a magnetic sensor having the whole detecting element covered with a molded resin, when the detecting element is arranged in a predetermined positional relationship with respect to the pulser ring, an inner peripheral side of the mold resin interferes with the large diameter shaft portion of the drive shaft in some cases. Such interference is not preferable.